greedy/max_capacity: fix myMax algorithm error (#1784)

Co-authored-by: wujing <[email protected]>

Author: realwujing

codes/c/chapter_greedy/max_capacity.c

@@ -12,7 +12,7 @@ int myMin(int a, int b) {
 }
 /* 求最大值 */
 int myMax(int a, int b) {
-    return a < b ? a : b;
+    return a > b ? a : b;
 }
 
 /* 最大容量：贪心 */